Disintegration boosts methane yield and masks dose-dependent MP interference in thermophilic digestion
Journal of Environmental Chemical Engineering, cilt.14, sa.6, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 14 Sayı: 6
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jece.2026.125617
- Dergi Adı: Journal of Environmental Chemical Engineering
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC
- Anahtar Kelimeler: Additive leaching, Alkaline-thermal disintegration, Polypropylene microplastics, Thermal-enzymatic disintegration, Thermophilic anaerobic digestion
- Orta Doğu Teknik Üniversitesi Adresli: Evet
Özet
Polypropylene (PP) is the dominant microplastic found in sewage sludge, yet it remains significantly underrepresented in anaerobic digestion (AD) literature. This knowledge gap is especially critical under thermophilic conditions, where elevated temperatures can alter polymer thermodynamics, accelerate plastic aging, and trigger the leaching of additives. Furthermore, how sludge pretreatments intersect with microplastics (MPs) remains unresolved. This study provides the first comprehensive evaluation of PP MPs in thermophilic AD integrated with alkaline-thermal (AT) and thermal-enzymatic (TE) disintegration. Both treatments enhanced solubilization, with AT achieving a higher degree of disintegration (DD, 67.0%) than the milder TE treatment (DD, 46.5%). In biochemical methane potential assays, the enhanced solubilization achieved by AT governed the methane production response, increasing methane yields by up to 32.0% (420.6–446.7 mL CH4 g⁻¹ VSadded) and apparently masking the dose-dependent effects of MPs. Conversely, untreated control reactors exhibited concentration-dependent methanogenic suppression at high doses (≥6 mg g−1 TS). TE pretreatment yielded 405.5–417.4 mL CH4 g−1 VSadded by liberating bioaccessible monomeric substrates. Modified Gompertz modeling revealed that while enzymatic depolymerization introduced a brief lag phase (3–4 d), it bypassed mass-transfer limitations by disrupting the dense physical shielding of the sludge matrix that aggregates MPs, progressively reducing lag phases at higher doses. SEM, FTIR, and DSC confirmed early-stage surface weathering, while target plastic additives (DEP, DBP, DEHP, BPA) remained confined to ppb levels. From the results, it can be deduced that both AT and TE are promising disintegration methods, that can shield thermophilic consortia from disruptions imposed by dominant plastic contaminants.